“Genes can be turned on or off, but they do not go away”

Alexandra Güntzer: Together with Dan Belsky and Avshalom Caspi you have recently reported on the ‘Genetics of Success’ – what exactly is behind this “genetic score”? And what does it help predict?

Terrie Moffitt: We calculated what is called a “polygenic score” for each of the 1000 members of the Dunedin Study, by using their DNA from a blood sample each person gave. Polygenic scores count up all the hundreds or thousands of genes in each person’s whole genetic makeup that are associated with a particular outcome. The outcome could be a characteristic (like height), an illness (like asthma) or a behavior (like dyslexia). In the case of our research project, we used a list of genes that are already known since 2013 to be linked to the outcome of educational attainment. We said, OK, so it’s already known that people who carry fewer of these genes tend to leave school very young whereas people who carry more of these genes tend to complete more schooling, right up to higher professional degrees. But what ELSE can this polygenic score tell us about a person? We wanted to find out how the genes actually work during a life.

AG: If these genetic discoveries for educational attainment are not related to education only, what else do they predict?

TM: We found that this same score, which up to now only predicted educational degree, begins acting on children early in life and extends through adulthood. Kids with higher polygenic scores started saying their first words earlier when they were toddlers, and then they learned to read faster than other children in their class. As they grew into adolescence, they were more ambitious; they often thought about going further in school and the kinds of jobs they said they wanted when they grew up were more responsible, and higher paying jobs. When they did grow up and became adults, individuals with higher polygenic scores were more likely to move away from their hometown and emigrate in search of opportunities, they built more successful careers, in the middle of life they were better at managing their money, and they fell in love with partners or spouses who had higher levels of education and greater earnings.

AG:And what about social context – is there a chance for upward social mobility if a child is born poor?

TM: Higher polygenic scores were associated with social mobility – children with higher polygenic scores tended to achieve more socioeconomic success even if they were born into families that were relatively poor. This suggests that if a person wins in the genetic lottery, this can help them to be resilient and do well in life, even if they happen to be born into a resource-poor environment.

“If a person wins in the genetic lottery, this can help them to be resilient and do well in life, even if they happen to be born into a recourse-poor environment.”

AG: What about psychological characteristics – do they play a role in context of genetic associations?

TM: Psychological characteristics accounted for genetic associations with life success outcomes, and these included a child’s intelligence, but also self-control and interpersonal skills, for example being friendly and outgoing, confident to interact with other children and adults. In other words, much of the reason that genes can predict who succeeds is that they give a child a slight edge on the talents that make for a successful person.

AG: Do genes provide a formula foolproof enough to make predictions about a child’s development?

TM: It is important to understand that the polygenic score predicted life success with only very modest accuracy. If anyone attempted to predict their own child’s future using this score, prediction would be wrong as often as it would be right. So, why are scientists excited about this work? I think we scientists get excited about learning something that has never been known before.

AG: Why and in which contexts are the ‘Genetics of Success’ important?

TM: Humans have been around a long, long time. It’s not hard to imagine that in our ancient history, the earliest humans who survived harsh conditions were those who were best able to communicate, who were able to attract other people to like them and help them, who were willing to travel far if necessary to find resources, and who found a mate who was also good at getting resources. These findings help us to understand how our genes enabled us to be successful, not just today, but always.

AG: If currently we are able to show associations will we in the future be able to establish causality and make more precise predictions?

TM: Causality is already established, and this is because the DNA is a root cause; consider that everything else in life comes after it, and a person’s basic genetic endowment isn’t altered by life. Genes can be turned on or off, but they do not go away. So we now can say confidently that genetic endowment is one of the real causes of educational attainment and of other aspects of life success that we studied. However, it’s a very, very weak cause. I think it will remain weak, in part because each gene has only a fractionally miniscule effect, and in part because life contains so very many other things that are bigger causes of educational attainment and life success.

“We now can say confidently that genetic endowment is one of the real causes of educational attainment and of other aspects of life success.”

AG: So, if I’m not achieving I cannot simply sit back and say “it’s in my genes”.

TM: For most students, blaming failure on genes would not convince a teacher. My mother was a teacher, and she never fell for this excuse, although I tried it many times.

AG: You have come up with the ‘Genetics of Success’ in context of your Dunedin studies, which you started in 1972 and which obviously is a rich source for groundbreaking research findings. And science is all about data. How does a young scientist get access to such great data these days?

TM: The ideal way to get access to data is to collect them yourself, because then you experience the scientific process from beginning to end, you attain a truly deep understanding of what you are studying, and because doing so makes the work of science much more fun. Of course, we understand that this ideal isn’t always possible. In which case the best approach is to network with research teams who are collecting data, to join in collaboratively, and benefit from coaching by the study investigators. Just grabbing a data set off the shelf is thin gruel, as compared to the richer feast of doing collaborative research in a mentor-apprentice relationship.

Prof. Terrie Moffitt studies how genetic and environmental risks work together to shape the course of abnormal human behaviors and psychiatric disorders. Her particular interest is in antisocial and criminal behavior, but she also studies depression, psychosis, and addiction. She is a licensed clinical psychologist, who completed her clinical hospital training at the UCLA Neuropsychiatric Institute (1984). Terrie Moffitt is associate director of the Dunedin Longitudinal Study, which follows 1000 people born in 1972 in New Zealand.